1. Field of the Invention
The present invention relates to the use of carbon black products in EPDM, HNBR, and butyl rubber compositions to provide increased modulus and increased bound rubber as well as other valuable properties.
2. Discussion of Related Art
EPDM, HNBR, and butyl rubber are well known rubber compositons used in a wide variety of industrial and consumer products. See McGraw-Hill Encyclopedia of Science & Technology, pp. 761-763 (McGraw-Hill, 1982). EPDM is a copolymer of ethylene-propylene-diene monomers. HNBR is a partially hydrogenated copolymer made from the copolymerization of acrylonitrile and butadiene. Butyl rubber is a copolymer of isobutylene and isoprene.
EPDM, HNBR, and butyl rubber compositions are used in a wide variety of products. These products include, for example, automotive parts, gaskets, cable and wire coatings, mechanical rubber products, cover strips for the sidewalls of tires, innertubes for tires, safety bumpers, fabric coatings, electrical wire insulation, hoses, mechanical rubber goods, and sealants for ponds or reservoirs.
One characteristic of EPDM, HNBR, and butyl rubber is their low levels of unsaturation. The low level of unsaturation in EPDM, HNBR, and butyl rubber limits the effectiveness of reinforcing agents in rubber compositions made from these rubbers. This is particularly true when compared with the use of reinforcing agents in diene rubbers which have high degrees of unsaturation. Butyl rubber, for example, is generally a polybutylene with 0.5-4.5% of a diolefin, normally 3% isoprene. The small amount of diolefin in butyl rubber provides unsaturation for reinforcement and crosslinking.
Carbon blacks have been utilized as pigments, fillers, and/or reinforcing agents in the compounding and preparation of rubber compositions. The properties of the carbon black are important factors in determining various performance properties of the rubber composition containing the carbon black. See, for example, U.S. Pat. No. 5,236,992, which is incorporated herein by reference.
It would be desirable to develop a carbon black product which would impart desirable properties to EPDM, HNBR, and butyl rubber compositions containing the carbon black product.